The digital pen by LogicTech is an example of a writing instrument that can record the movement of the pen in order to recall it electronically so that what is written by the pen can be easily digitized. The prior art digital pen includes an optical sensor or camera, which tracks the movement based on special “grided” paper. The pen is bulky and works with the special paper for recording purposes.
Other inventions for tracking motion have been numerous, such as which measure motion based on accelerometers or gyroscopes. These include patents assigned to Vega Vista, Inc. of Mountain View, Calif. which are hereby incorporated by reference and others. The use of accelerometers for motion in 3 dimensions is computationally difficult, especially on a minute scale. The tablet computer systems use various ways to track the motion of the stylus' but the motion detection is taking place through electronics in the computer screen and not the stylus and thus cannot be used independently.
What is needed however, is a compact tracking and recall system, which is portable and light and does not require special paper. Furthemore, the computational problems associated with standard movement devices accelerometers and gyroscopes makes internal calculation of movement more difficult, so the need for a simpler recording mechanism is apparent.